update readme for .Net 6 instructions

Author: jjw24

Plugins/Flow.Launcher.Plugin.WebSearch/Settings.cs

@@ -225,4 +225,4 @@ public string Suggestion
 
         public bool OpenInNewBrowser { get; set; } = true;
     }
-}
+}

README.md

@@ -278,8 +278,8 @@ Get in touch if you like to join the Flow-Launcher Team and help build this grea
 
 ### Developing/Debugging
 
-- Flow Launcher's target framework is .Net 5
+- Flow Launcher's target framework is .Net 6
 
-- Install Visual Studio 2019
+- Install Visual Studio 2022
 
-- Install .Net 5 SDK via Visual Studio installer or manually from [here](https://dotnet.microsoft.com/download/dotnet/thank-you/sdk-5.0.103-windows-x64-installer)
+- Install .Net 6 SDK via Visual Studio installer or manually from [here](https://dotnet.microsoft.com/en-us/download/dotnet/thank-you/sdk-6.0.300-windows-x64-installer)